1. Field of the Invention
The present invention relates to a fiber reinforced cement composition using a hydraulic inorganic material such as cement, products thereof and a manufacturing process thereof.
2. Description of the Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
Hitherto, for manufacturing process of fiber reinforced cement product using a hydraulic inorganic material such as cement, when the specific gravity of fiber reinforced cement product is high by adding a lot of powder, freezing and fusion resistance and bending strength improve basically.
But, if the product is hard by high specific gravity thereof, there is a problem in installing property such as nail performance.
And, for reason to improve of physical properties, about powder material, addition of various lightweight aggregates is examined.
For example, in Japanese Patent No. 3374515, it is disclosed that the amount of not less than 5% by mass and not more than 30% by mass of vermiculite adds in cementitious molding composition.
In Japanese unexamined laid open patent publication No. 2000-264701, it is disclosed that wood fiber which specified average fiber length and average width of fiber adds in matrix, furthermore, the amount of not less than 18% by mass and not more than 60% by mass of expanded inorganic material such as expanded perlite adds in matrix.
And, in Japanese patent Publication No. H08-32603, it is disclosed that lightweight cementitious molding composition for extrusion comprising cement, lightweight aggregate, inorganic aggregate, organic fiber, additive of cellulose type, in which lightweight aggregate is fly ash which has average particle size of not more than 2 mm, has a bulk specific gravity of not less than 0.1 and not more than 0.4, and inorganic aggregate comprising (A) and (B), in which inorganic aggregate (A) is spherical aggregate which has a particle size of not less than 1 μm and not more than 100 μm selected out of fly ash and spherical calcium silicate hydrates, in which inorganic aggregate (B) is a ultra-fine particle aggregate which has a particle size of not less than 0.01 μm and not more than 0.5 μm selected out of micro-silica, silica fume, natural pozzolan, diatomaceous earth, silica flower, aerosol.
Here, a lightweight cementitious composition is for extrusion, and lightweight aggregate and inorganic aggregate are quite spherical, because it is to get reduction of extrusion pressure of an extrusion and fluency of an extrusion.
However, in not extrusion that is wet forming such as Hatschek process and flow on process, it mixes raw materials with water, and it makes a slurry of raw materials flow down on a felt, and it is aspirated from under the felt and it dehydrates, there is danger that lightweight aggregate, particularly, hollow lightweight aggregate rise from the slurry in forming process and gather in the surface side, and there is danger that unevenness occurs to specific gravity of products, and there is danger that delamination occurs when a green sheet is rolled up around a making roll.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. For example, certain features of the preferred embodiments of the invention may be capable of overcoming certain disadvantages and/or providing certain advantages, such as, e.g., disadvantages and/or advantages discussed herein, while retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.